in order to investigate the contribution of ear photosynthesis and cytokinin in determining grain sink size, a pot study was conducted during january to june 2005 in cereal glasshouse of faculty of agriculture of karaj, iran. experiment was conducted in a complete randomized design with a factorial arrangement of two factors, three replications and four pots in each plot. factors included culti...

When stressed by low soil water content (SWC) or high vapor pressure deficit (VPD), plants close stomata, reducing transpiration and photosynthesis. However, it has historically been difficult to disentangle the magnitudes of VPD compared to SWC limitations on ecosystem-scale fluxes. We used a 13 year record of eddy covariance measurements from a forest in south central Indiana, USA, to quantif...

In this study, we aimed to assess how sample sizes affect confidence of stand-scale transpiration (E) estimates calculated from sap flux (F(d)) and sapwood area (A(S_tree)) measurements of individual trees. In a Japanese cypress plantation, we measured F(d) and A(S_tree) in all trees (n = 58) within a 20 x 20 m study plot, which was divided into four 10 x 10 subplots. We calculated E from stand...

Linking sap flow in tree boles to plant transpiration continues to be a fundamental and practical research problem in physiological ecology and forest hydrology. Many models have been proposed to describe water movement within trees with varying degrees of success. The prevailing resistance–capacitance (RC)-circuit models have the advantage of being easy to implement. However, RC models are ord...

An isothermal boundary layer analysis is presented for the convection flow of a second-order non-Newtonian fluid past a two-dimensional wedge embedded in a non-Darcian porous medium in the presence of significant thermal radiation, surface transpiration and Eckert viscous heating. Nonsimilar numerical solutions are generated for the shear stresses and local heat transfer rates at the surface of...

BACKGROUND AND AIMS Grapevines growing in Australia are often exposed to very high temperatures and the question of how the gas exchange processes adjust to these conditions is not well understood. The aim was to develop a model of photosynthesis and transpiration in relation to temperature to quantify the impact of the growing conditions on vine performance. METHODOLOGY Leaf gas exchange was...

We describe a porometer that enables continuous monitoring of the stomatal diffusive resistance of leaves. The flux is measured of a gas-such as nitrous oxide-diffusing through a leaf that divides an enclosing chamber into two compartments. Nitrous oxide is added in known concentration to the airstream passing through the compartment on one side of the leaf and is recovered from the airstream p...

Continental precipitation not routed to the oceans as runoff returns to the atmosphere as evapotranspiration. Partitioning this evapotranspiration flux into interception, transpiration, soil evaporation, and surface water evaporation is difficult using traditional hydrological methods, yet critical for understanding the water cycle and linked ecological processes. We combined two large-scale fl...

1 Linking sap flow in tree boles to plant transpiration continues to be a fundamental and 2 practical research problem in physiological ecology and forest hydrology. Many models have 3 been proposed to describe water movement within trees with varying degrees of success. The 4 prevailing resistance-capacitance (RC) circuit models have the advantage of being easy to 5 implement. However, RC mode...